This invention relates to the fabrication of a heat exchanger coil and, in particular, to a method of heating the tubular joints of the coil during fabrication.
More specifically, this invention relates to the fabrication of a heat exchanger coil for use in a refrigeration system; the coil having complex refrigerant flow circuitry contained therein.
The term coil, as herein used, refers generally to a heat exchanger having a series of parallel rows of tubes running transversely through a fin package made up of spaced apart planar heat transfer surfaces. Refrigerant is circulated through the tube rows while ambient air is directed over the heat exchanger fins by means of a fan or the like.
In a complex coil of this nature, the parallel rows of tubes are interconnected by means of return bends and crossover tubes to form a number of refrigerant flow circuits that are strategically positioned within the fin package. By selectively controlling the operation of the circuits, the capacity of the heat exchanger can be varied in response to the load demands placed upon the air conditioning system.
Typically, the tube rows making up the various circuits are tightly spaced within the fin package. As a consequence, the components interconnecting the rows to form the various circuits, as well as those components needed to bring refrigerant into and out of the circuits, are tightly packed within a very confined area. Often times, the tubular connections are required to pass one over the other. Proper heating of the connector joints during the formation of the coil assembly has long been a problem in the art because of the close compactness of the components within the joint region. As can be seen, the tightly spaced tubular components serve to shield one another from most conventional heat sources, such as spear flame guns or radiant heat lamps. Furthermore, the shadowing components, because they lie closer to the heat source than the joint to be treated, are in constant danger of being overheated and thus thermally damaged.